Graphene has been shown to be an excellent material for use as the channel layer in field effect transistors (FETs). It exhibits high carrier mobility and low noise properties. However, the manufacture of FETs with graphene channel layer has met with certain problems.
One such problem is that the gate dielectric, which must be present between the graphene layer and the gate electrode, usually causes severe degradation of channel mobility in the graphene layer. Commonly used methods for depositing high-K gate dielectrics include atomic level deposition (ALD) and evaporation.
For ALD high-k gate dielectrics, the coverage of the high-k film on graphene is usually poor. To enhance coverage, surface pre-treatment or seed layer are usually used. Such surface pre-treatment or seed layer usually causes severe doping of the graphene and can cause mobility degradation as well. Evaporated high-k gate dielectrics also demonstrate the same problem of degrading mobility of electrons in the graphene layer.